Conduit lines or sewer pipes which are buried underground sometimes have concrete flowed together with water solidified within them, and a gap between the conduits because a joint of the conduits are displaced due to ground subsidence or road construction, or deviated levels between the connected conduits. Besides, a solidifying chemical fed may leak into a pipe through a gap to form a solidified substance within the pipe, or tree roots could invade pipes to block them. Therefore, it is necessary to smooth the pipe interior for remedying the deviated levels of the pipes, cutting and removing foreign substances from the pipe interior, or washing the pipe interior. In replacing old cables in an underground conduit line with new cables, the old cables must be cut and removed because the old cables sometimes block the pipe interior and cannot be pulled out.
In order to meet the above requirements, the following methods have been employed.
A first one uses a water jet, and a second one inserts into a conduit line a device equipped with a shaft which is provided with a cutter or drill at its end and rotates the shaft by an electric or hydraulic drive source positioned outside of the conduit line. Another method was also used in which a cutter was mounted on an output shaft of a hydraulic motor, and inserted into a conduit line to smooth, remove or wash.
But, such conventional methods had the following disadvantages. First, the fluid cleaning with a water jet was hard to smooth a hard substance. But, this problem was solved to some extent by rotating the jet nozzle and also controlling its rotation. However, the impact force of the water jet alone was insufficient to satisfactorily smooth firmly solidified concrete or mortar within a conduit line.
To solve such a problem, a cutter may be rotated to provide a high cutting force. For a device which uses such a rotating cutter, a method employed transmits the rotation of a drive source disposed outside of the conduit line to the cutter at the front end through several shafts and performs smoothing. But, since this method suffers from a heavy loss of power because of deformation of the shafts and also workability is lowered, the drive force is required to have a high power, and many workers are required in charge. Besides, when a conduit line is curved, there is a fear of a damage to the conduit line because the shafts or joints are contacted with the interior of the conduit line.
When the hydraulic motor having the cutter mounted on the output shaft is inserted into a conduit line, oil hydraulic hoses are required to be two for feeding and returning, causing the conduit interior complicated when they are inserted into the conduit line.
To remedy the above disadvantages, the applicant of this invention has disclosed a hydraulic motor having a high-precision small turbine which is rotated at a high speed with water under a high pressure and a low flow rate in Japanese Patent Publication No. 62-2149. This hydraulic motor is used as an underwater hand tool with a hammer, grinder, drill, impact wrench or the like mounted at the end of the motor, and a cast turbine is used to rotate the tool at the end.
As shown in FIG. 8, a hydraulic motor 39a' has a high-pressure water feed port 27', a turbine 25', a water nozzle 26', and a low-pressure water discharge port 28'. This hydraulic motor is configured to supply pressurized water from the high-pressure water feed port 27', inject the pressurized water to the turbine through the water nozzle 26' to rotate the turbine, and drive the hydraulic motor 39a'. The turbine 25' and the water nozzle 26' are produced by welding or casting.
The applicant has also disclosed a smoothing device which uses the cast turbine motor of the above hydraulic motor to enable the insertion into a conduit line and is provided with a discharge injection mechanism to discharge removed debris and to propel itself in Japanese Patent Application No. 5-350036.
As shown in FIG. 10, this smoothing device is configured that a cutter 5a" is mounted as cutting means on an output shaft at the end (a travelling direction) of a hydraulic motor 39a" as hydraulic drive means, high-pressure water is supplied from a high-pressure water feed device through a high-pressure water hose 4a" to drive the high-power hydraulic motor 39a" by the water pressure, and the cutter 5a" mounted on the end of the output shaft is rotated.
Smoothing work using this smoothing device is performed as follows. Namely, smoothing is performed by the cutter 5a" which is drivably connected to and rotated by the hydraulic motor 39a" through the output shaft. Then, the smoothed portion is washed by the pressure of water injected from low-pressure injection nozzles and a high-pressure nozzle which are open toward a direction of the motor travels, and the removed debris is discharged backward from a low-pressure injection nozzle and high-pressure injection nozzles which are open backward. A propelling shaft 3a" is attached to a propelling shaft moving apparatus and is composed of a plurality of connecting shaft elements 3b", 3c", . . . connected by universal joints 43". Rollers 42" are disposed in the vicinity of connected portions, contacting the conduit interior, so that the propelling shaft moves in the conduit interior easily and that the propelling force can be transmitted by the propelling shaft 3a" easily. By the smoothing device using this small hydraulic motor, smoothing can be performed continuously, technologies concerning removal of hardened wastes from pipes in public works were extremely improved.
But, in the case of the device which smooths by the rotating cutter as disclosed in Japanese Patent Application No. 5-350036, the cutter is not always positioned at almost the center of the pipe interior, and there is a fear of a damage to the pipe interior due to an undesirable contact with the inner wall of the pipe which is in appropriate position when the device itself is displaced from the center position exceeding a prescribed level or the cutter is tilted because of irregularity of the pipe, uneven substances remained without being removed by the cutter, or accumulation of foreign substances.
Besides, since the smoothing device disclosed in Japanese Patent Application No. 5-350036 has a cylindrical motor, the removed debris tends to be caught on the outer periphery of the motor, and the front end face of the motor which is travelling is readily blocked by the debris within the pipe. Therefore, to use the hydraulic motor for the smoothing device, the appearance of the hydraulic motor or that of a device using the hydraulic motor still needs to be improved.
Since a conventional hydraulic motor used for the smoothing device is driven by a water pressure, there is an inevitable problem that the turbine and the water nozzle have a shortened service life because of the water pressure, and they must be replaced frequently. Regardless of such disadvantages, the conventional turbine and water nozzle are produced by casting or welding, making their maintenance troublesome.
Besides, when a conduit line is long or substances to be cut and removed are rigid, there is another problem that the removed debris cannot be discharged easily. When a conventional smoothing device which does not have discharge means is used, every after removing a certain amount of rigid substances, it is necessary to pull the cutter bit out of the pipe and to discharge the removed debris from the pipe.
To remedy such a disadvantage, Japanese Patent Laid-Open Publication No. 7-75228 discloses another smoothing device. This smoothing device has a hydraulic motor which provides cutting blades with a rotating force, and discharges the removed debris resulting from smoothing by the drainage from the hydraulic motor and by causing a water flow within a smoothed hole by the high water pressure injection nozzle provided on the hydraulic motor.
However, in the smoothing device disclosed in Japanese Patent Laid-Open Publication No. 7-75228, the flow rate of the drainage within the smoothed hole is decreased as separated from the injection nozzle and when the removed debris has a high specific gravity, it was feared to settle and block the smoothed hole. And, a propelling shaft and a high-pressure water hose which are connected to the hydraulic motor are inserted into the smoothed hole, but when the drainage has a slow flow rate, the removed debris is involved in the drainage to block the pipe.
And, since long and continuous debris which is produced when waste such as plastics is removed is easy to block a pipe, it is necessary to intermittently perform smoothing, or lower a smoothing speed, thereby lowering the smoothing efficiency.
When a pipe has a hole, a curve or inclination, water tends to accumulate within the pipe, and it is necessary to drain the pipe after smoothing. And, when a feeder which has one feed threaded shaft is a rack and pinion type, its attaching direction is limited, and when the threaded feeder is an ordinary one, a guide mechanism for preventing a moving element from turning together is required. Thus, it is disadvantageous that the structure is complicated, and its weight is increased, resulting in poor transportability.
And, it is impossible to tie a rope to the front of the cutter of the device and pull it in the longitudinal direction of the pipe conduit because the rope is twisted due to the rotation of the cutter. Therefore, the device can be pulled only to the side opposite from the cutter, and this is inconvenient for using the device.
There is also a disadvantage that when the cutter is placed within the pipe conduit, the whole device is not always visible, and even when the cutter comes in contact with the inner wall of the pipe, it cannot be known whether the cutter is at a position where the connected pipes are not on the same level or the cutter is not at about the center of the pipe, causing an unnecessary contact.